A halogen-CFL bulb is a relatively new kind of light bulb developed by General Electric (GE). It's called a hybrid bulb that combines halogen and compact fluorescent (CFL) technologies into one light bulb. This is done in an attempt to take advantage of the best of both technologies and eliminate some of the common complaints about energy efficient light bulbs. One of the primary benefits of the halogen-CFL bulb is that it provides bright light immediately, yet retains a high degree of energy efficiency.
GE developed the new light bulb in an attempt to improve consumer satisfaction with available energy efficient lighting options. The shape of a halogen-CFL bulb is very similar to that of a traditional incandescent light bulb, with a narrow base and a rounded, bulbous top. The inside is completely different from incandescent lighting technology, however, and actually combines two newer technologies. When the hybrid bulb is turned on, it provides bright light right away by using the halogen light source until the CFL portion warms up and takes over.
Inside the outer covering of the halogen-CFL bulb is the compact fluorescent coil that is familiar to many. GE uses the smallest coil available; in the center of the coil is a tiny halogen bulb. The two technologies work together to provide a light source that uses much less energy than traditional incandescent bulbs while avoiding some of the drawbacks of the newer lighting. A few examples of the problems customers have had with energy efficient lighting include incompatibility with some existing light fixtures, the heat generated by halogen, and the long amount of time for the CFL to reach full brightness.
Many of standard CFL bulbs available do not fit correctly in older light fixtures, leading to ill-fitting shades and coverings or exposed coils that many people find unattractive. GE uses the shape of the outer covering and the small size of the compact fluorescent coil to allow the halogen-CFL bulb to fit properly in light fixtures that were designed when incandescent bulbs were still in common use. Halogen light sources provide bright light, but also are incompatible with older light fixtures. Halogen generates a lot of heat and isn't always considered safe due to the danger of fire. The halogen-CFL bulb solves this issue by only utilizing the halogen for a short period of time.
According to GE, one of the main benefits of the halogen-CFL bulb is the instant availability of bright light in contrast to standard CFL light bulbs. A typical CFL takes a while to reach full brightness; this was a common cause of customer complaints. The hybrid halogen-CFL bulb uses the halogen light source to overcome this time lag; it provides immediate bright light during the time that the CFL is gradually reaching full brightness. Once it's fully lit, the CFL takes over and the halogen part switches off to save energy.